Liquefied gas pressurizing systems



Dec, 4, 1956 .1.J. sHANLEY 2,772,545

i LIQUEFIED GAS PRESSURIZING SYSTEMS IN V EN TOR.

De'c. 4, 1956 J. J. sHANLEY' 2,772,545

LIQUEFIED GAS PRESSURIZING SYSTEMS IN V EN TOR.

Dec. 4, 1956 J. J. sHANLEY 2,772,545

LIQUEFIED GAS PRESSURIZING SYSTEMS l Filed May 15. 1952 4 Sheets-Sheet 3United States Patent() LIQUEFIYED GAS PRESSURIZNG SYSTEMS -.lames J.Shanley, Bethesda, Md., assigner to Air Products,

Incorporated, a corporation of Michigan Application May 13, k1952,Serial No. 287,650 23 ciaims. (ci. sz- 122) This invention relates topumping of liquefied gases, in liquid phase. More particularly, itrelates to methods of and apparatus for transferring a volatile liquidfrom a supply source at low pressure to a receiving means under arelatively high pressure, such as the liquid product of a gas separationoperation in which a gaseous mixture is fractionated to produce avolatile liquid as a product.

As is well known, volatile liquids held at low pressure, such as liquidoxygen and nitrogen or liquefied petroleum gases, have extensive.utility in gaseous phase at relatively high pressure. ln general thereare two methods for transferring volatile liquid at low pressure intogaseous form at a relatively high pressure. According to the rst methodthe volatile liquid is vaporized at the low pressure and thereaftercompressed in gaseous phase to the desired high pressure. Practice ofthis method requires a gas holder of large over-all dimensions andpresents serious gas compression problems, such as lubrication of thecompressor and explosion hazards especially in the case of compressinggaseous oxygen. In the second method the volatile liquid is pumped inliquid phase to the desired relativelylhigh pressure and then the highpressure liquid is converted into gaseous form by a suitable vaporizingprocess.v The volatile liquid is pumped in liquid phase to the desiredhigh pressure by means of a mechanical pump usually of the plungertype'designed especially for .pumping highly volatile liquids. Thismethod requires that the liquid be subcooled before entering the pumpand the pump must have special plunger packing and include insulatingmeans to prevent heat infiltration and cold losses. For bestperformance, provision is made for cooling the liquid conveying end ofthe pump with a lluid colder than the liquid being pumped to preventpump stoppages due to vapor lock. While liquid pump arrangements of theforegoing character have proven quite adequate and by far the best Isystem available they are not capable of continuous and uninterruptedperformance inasmuch as the moving elements and packing requirereplacement as in the case of all mechanical machines including movingparts. This is especially the case in pumps of this character where thepacking and other elements are designed tominimize heat of friction. l,

It is therefore an object of the present inventionto provide a novelmethod of and apparatus for pumping volatile liquids Without employingmoving mechanical elements for producing the pumping force. n

Another object is tol provide a novel mcthodof and apparatus for pumpingvolatile liquids without requiring th use of pump packing orsimilarmaterials. Y

Another object is to provide a novel method of an apparatus for pumpinghighly volatile liquids which com-V I 2,772,545 Patented Dec. 4, 19,56

ICC

phase a volatile liquid from a fractionating operation to a receivingmeans under a relatively high pressure.

Still another object is to provide a novel method of and apparatus fortransferring in liquid phase a volatile liquid from a fractionatingoperation to a receiving means under a relatively high pressure byutilizing the influence of gravity and only a small quantity ofadditional energy that may be obtained from the fractionating operationand readily replaced by merely slightly varyingthe temperature orpressure of the gaseous mixture feeding the fractionating operation.

Still another object is to provide la novel method of and apparatus fortransferring in liquid phase a volatile liquid material from 'a' storagereservoir to a receiver under a relatively high pressure through atransfer zone relatively positioned to receive liquid from the storagereservoir and deliver liquid to the receiver under the inuence ofgravity.

Still another object is to provide a novel method of and apparatus fortransferring in liquid phase a volatile liquid from a fractionatingoperation to a receiver under a relatively high pressure through atransfer zone relatively positioned to receive liquid from thefractionating operation and deliver liquid to the receiver under theinfluence of gravity responsively to different pressure conditionsestablished by employing fluids from the fractionating operation withoutsubstantial effect upon fractionating efficiency.

A still further object of the present invention is to provide a novelmethod of and apparatus for fractionating a gaseous mixture and forproviding a liquid product from the fractionation in gaseous phase undera relatively high pressure by pumping the liquid product to a relativelyhigh pressure and passing the high pressure liquid product in heatexchange relation with the gaseous mixture on its way to thefractionation without employing mechanical pumping apparatus or devicerequiring pump packing or equivalent structure, in a substantiallycontinuous operation.

A still further object is to provide a fractionating operation forseparating gaseous mixtures including a novel volatile liquid productpumping method and apparatus which effects operation of thefractionating operation to compensate for certain temperaturefluctuations which occur during certain phases of operation.

Other objects and features of the present invention will appear morefully from the following detailed description considered in connectionwith the accompanying drawings which disclose several embodiments of theinvention. It is expressly understood however that the drawings aredesigned for the purpose of illustration only and not as a definition ofthe limits of the invention, reference for the latter purpose being hadto the appended claims.y

In the drawings, wherein similar reference characters denote similarelements throughout the several views:

Fig. l is a diagrammatic view illustrating one form of the presentinvention in connection with a fractionating cycle; l

Fig. -2 is a diagrammatic view illustrating a modified form of theinvention; v i

Fig. 3v is a diagrammatic view illustrating afractionating cycleincluding another form of the present invention;

Fig. 4 is a diagrammatic view illustrating a fractionating cycleincluding stillfanother form of the present invention, and

Fig. 5 is a diagrammatic viewin section illustrating a solenoid operatedvalveV that may be used with the' presditions to allow this phenomenonto take place.

the liquid to a receiving means under a relatively high linternalpressure of the transfervessel is at least equal to the low pressure ofthe supply source, while during the other conditiony the internalpressure is at least equal to Y.

`the relatively high pressure of the receiving means. Es-

tablishment of the relative high pressure condition determines the timeof the pump strokes or `pressurizing action, while the frequency of theoccurrence of this condition is a measure of the pump capacity. Transfervessel low pressure conditions occur at the same frequency and in propertime relation with the high pressure conditions to allow high speedpumping. The energy required to operate the pump is low inasmuch as theactual transfer of liquid talies place under-the influence of gravitywhile energy is employed only to establish equalized pressure con- Thuswhen the principles of the present invention are incorporated in afractionating cycle, as disclosed, very little energy is ltaken from thecycle for the pumping operation with a substantially immaterialreduction in fractionating efficiency which may be easily compensatedfor by merely slightly increasing the pressure of the gaseous mixturefeeding the cycle, where that is possible. While the several embodimentsof the invention are disclosed in connection with fractionating cyclesfor the separation of air into its major constituents oxygen andnitrogen, it is to be expressly understood that the principles of thepresent invention are equally applicable in fractionating apparatus forseparating gaseous mixture other than the atmosphere and may be utilizedin cycles other than fractionating cycles.

A pumping system embodying the principles of the present invention isdisclosed in Fig. l of the drawings 1n connection with a fractionatingcycle including a primary heat interchanger lil and a fractionatingcolumn 1l. 'The Vheat interchanger ll) includes two banks of tubes l2,l2 and 13, i3 surrounded by an outer shell 14 to provide threepassageways in heat exchange relation with one another. Thefractionating column is of the conventional two stage type including ahigh pressure zone and a low pressure zone 16, however the presentinvention may be utilized in connection with single stage fractionatingcolumns. The high and low pressure zones are each provided with a stackof bubbling plates 17 and are separated by a partition 1.3 and aconventional refluxing condenser l9. The gaseous mixture to befractionated, which may comprise compressed and cooled air free frommoisture and` other impurities, enters the system through a conduit 2t)and passes through the tubes 12, 12 of the primary heat interchanger inheat exchange relation with cold products of the fractionation cycle.The air stream leaves the lower portion of the primary heat interchangerat a substantially lower temperature, and is conducted by way of aconduit 21 through Van expansion valve 22, where its temperature andpressure are reduced, from which it enters the lower end of the highpressure zone 1S at or near its point of liquefaction. in the highpressure zone a preliminary fractionation of the air takes placeproducing gaseous nitrogen rising into thercondenser 19 and a liquidrich in oxygen collecting in a pool 23 in the base of the column. Thegaseous nitrogen is liquefied by heat interchange with a pool 24 ofvboiling liquid oxygen surrounding the condenser. VA portion of theliquefied nitrogen collects in a pool Z5, while the remainder fallsdownwardly as refiux for the high pressure zone. A stream of oxygen richliquid is removed from the pool 23 by way of a conduit 26,passedlthrough an expansion valve 27 anda secondary heat interchanger 2Sand is introduced by way of a conduit 28a at a medial point in the lowpressure zone as feed. A stream of liquid nitrogen is withdrawn from thepool 25 and conducted by a conduit 29 through another pass of the heatinterchanger 28 in heat exchange relation with the stream of oxygen richliquid. Thereafter, the subcooled liquid nitrogen is passed through anexpansion valve 30 and introduced into the top of the low pressure Zoneas reflux by way of a conduit 31. ln the low pressure zone thefractionation process is completed producing substantially pure oxygenin liquid phase collecting in the pool 24 above the plate 11.8, andgaseous nitrogen which flows upwardly and leaves the column through aconduit 32. The gaseous nitrogen is conducted by the conduit 32 to theshell 14 of the primary interchanger lo, in which it passes in heatexchange relation with the incoming air stream, and leaves the cycle atsubstantially atmospheric temperature and pressure by way of a conduit33 connected to the top of the primary interchanger 1lb.

In accordance with the principles of the present invention a novelmethod and apparatus are provided for transferring the liquid Voxygenproduct from the pool 24 to a receiving means under a substantially highpressure with respect to the pressure in the low pressure zone, such asto the vaporizer section 13, 13 of the heat interchanger 10 in which theliquid oxygen product forfeits cold to the incoming air stream andemerges from the heat interchanger in gaseous phase. For this purpose apressure or transfer vessel 3S is provided. The transfer vessel may beof cylindrical or rectangular shape to form a closed chamber 36, and isconstructed of suitable material to withstand a pressure in the chamberat least equal to the relatively high pressure developed in thereceiving means. For a purpose that will be described below, thetransfer vessel is preferably constructed of stainless steel or anyother material having a comparatively low thermal conductivity, or, ifconstructed of a material having good thermal conductivitycharacteristics, is then provided with suitable insulation to reduce therate of heat transfer from within to without the chamber. The transfervessel is centrally mounted in an enlarged vessel 37. The vessel 37 ismounted at an elevation with its top below the normal liquid level ofthe pool 24 and is in continuous communication with the liquid oxygenthrough a conduit 38. With this arrangement liquid oxygen normally fillsthe chamber 39 surrounding the transfer vessel 35. A vapor conduit 40 isconnected between the top of the vessel 37 and a point in the lowpressure zone above the liquid level of the oxygen pool for the removalof oxygen vapor that may be developed in the vessel 37 during thepumping operation. The transfer vessel is provided with inlet andyoutlet valves 41 and 42 located at the upper and lower ends of thevessel, respectively. The inlet valve opens inwardly to allow the .iiowof liquid oxygen from the chamber 39 to the chamberV 36 except when thepressure in the chamber 36 exceeds the pressure of the liquid oxygen inthe low pressure zone. The outlet valve 42, mounted in a well 43 formedin the bottom of the transfer vessel, allows the flow of liquid oxygenfrom the transfer vessel to an output conduit 44 except when thepressure in the conduit 44 exceeds the pressure in the chamber 36.'rl`he conduit 44 is connected to the lower end or bottom portion 45 ofthe vaporizer section 13, 13. The lower end of the primary heatinterchanger is at an elevation sufficiently below the vessel 37 toallow liquid oxygen in the chamber 36 to flow, under the influence ofgravity, to the vaporizer section when the requiredpressurerelationships exist. The liquid oxygen in the vaporizer sectionforfeits cold to the incoming air stream and leaves the interchanger ingaseous phase by way of a conduit 46 connected to the upper end or topportion i7 of the vaporizer section. The gaseous oxygen builds up to arelatively high pressure in the vaporizer section of v a valve dependingupon the manner of employing the gaseous oxygen delivered by the conduit46.

The arrangement for effecting the transfer of low pressure 'liquidoxygen in the chamber 36 to the vaporizer section of the heatinterchanger under a relatively high pressure comprises a pressureequalizing conduit 48 forming a connection between the upper end 47 ofthe vaporizer section and the chamber 36 of the transfer vessel 35. Theequalizing conduit is provided with a valve 49 controlled by a periodicvalve operator 50. The valve operator functions to open the valve 49 atregularly spaced intervals and to maintain the valve open for apredetermined duration which is short as compared to the period of thespaced intervals. The valve operator may comprise an electrical ormechanical timing device including an arrangement for producing acontrol signal at an adjustable frequency, while the valve 49 may be ofany suitable structure capable of the foregoing operation. For example,the valve may include a steel valve member in a brass casing and asolenoid positioned outside the casing to operate the valve member asdescribed more fully hereinafter.

it is understood that the fractionating column, the heat interchangerand the vessel 37 and associated conduits are suitably insulated inaccordance with conventional practice. Also, the various elements of theapparatus such as the transfer vessel 35, the vessel 37 and thevaporizer section are disclosed primarily to provide an adequateillustration of the invention, and it is eX- pressly understood that thedrawings do not necessarily represent the relative sizes of thecomponents of the apparatus.

In operation, the fractionating column functions in a conventionalmanner producing a gaseous nitrogen fraction and a liquid oxygenfraction as nal products from the incoming air feed. The gaseousnitrogen is removed from the top of the column by the conduit 32 andpassed in heat exchange relation with the incoming air stream, while theliquid oxygen fraction collects in the pool 24. The liquid oxygen flowsfrom the pool 24 through the conduit 38 into the chamber 39 surroundingthe transfer vessel 35. When the level of the liquid oxygen pool reachesthe height of the top of the transfer vessel, and when the internalpressure of the transfer vessel is not greater than the pressure of theliquid oxygen in the low pressure zone, liquid oxygen will flow from thecharnber 39 into the chamber 36 past the valve 41. Also, when thepressure in the transfer vessel is equal to or greater than the pressurein the conduit 44, liquid oxygen flows, under the influence of gravity,from the chamber 36 past the valve 42 into the lower end 45 of thevaporizer section 13, 13 by way of the conduit 44. The liquid oxygen isconverted to gaseous phase in the vaporizer section by forfeiting coldto the incoming air stream, and builds up to a relatively high pressuretherein as determined by the controls and/ or receiving means associatedwith the output conduit 46. Eventually the pressure in the vaporizersection exceeds the low pressure in the chamber 3S and the valve 42 iscaused to move to its closed position isolating the transfer vessel fromthe vaporizer section. Thereupon the chamber of the transfer vessel willcompletely fill with liquid oxygen at the low pressure. Under theseconditions the apparatus will transfer the maximum quantity of liquidoXygGn upon equalization of pressure between the transfer vessel and thevaporizer section. The pressure equalization occurs when the periodicvalve operator 50 functions to open the valve 49 so that the highpressure oxygen vapor from the upper end 47 of the vaporizer section isconducted to the chamber 36 through the conduit 48. Upon equalization ofthe pressures in the chamber 36 and in the conduit 44, the valve 42.opens and liquid oxygen ows under the influence of gravity from thetransfer vessel into the lower portion of the vaporizer section throughthe conduit 44 at whatever pressure may exist in the vaporizer 6section. The valve operator closes the valve 49 after a predeterminedperiod of time sufficient to allow the liquid oxygen to flow from thechamber 36 trapping a quantity of oxygen vapor in the transfer vessel.Since the transfer vessel is surrounded by the cold liquid oxygen in thechamber 39 the trapped oxygen vapor is cooled producing a pressure dropin the transfer vessel causing the valve 42 to move to its closedposition isolating the transfer vessel from the vaporizer section.Thereupon oxygen vapor in the chamber 36 continues to forfeit heat tothe surrounding cold liquid oxygen until such time that the internalpressure of the transfer vessel corresponds to the vapor pressure of theoxygen in the pool 24. Underthese conditions the valve 41 opens allowingliquid oxygen to flow into and till the chamber 36. Thereupon the valve49 is again opened to initiate the pumping cycle.

lt was mentioned above that the walls of the transfer vessel 35 areconstructed of a material having a loW thermal conductivity, such asstainless steel, or the transfer vessel is provided with suitableinsulation to establish a low rate of heat transfer between the chambers36 and 39. This arrangement controls the rate of condensation of thehigh pressure oxygen vapor in the chamber 36 to insure establishment ofthe pressure equalization and a rapid transfer of the liquid oxygen fromthe chamber 36 while at the same time allowing the oxygen vapor to becondensed following closure of the valve 49 so that the chamber 36 maybe refilled with liquid oxygen within a reasonable period of time. Ofcourse, for maximum pumping efficiency, the period of the periodic valveoperator should never exceed the total time required for the liquidoxygen to flow from the chamber 36 and for the chamber to be refilledwith liquid oxygen. The total time will be dependent in part upon thevolume of the chamber 36, and it may be desirable in some cases toprovide a transfer vessel of comparatively small volume and to operatethe periodic valve operator at a high frequency. This arrangement mayaid in maintaining a substantially constant liquid oxygen level in thevaporizer section and thus tend to stabilize the air feed temperature.

During the time the oxygen vapor is being condensed in the chamber 36,heat is added to the liquid oxygen surrounding the transfer vessel andany oxygen vapor that may evolve is returned to the low pressure zone ofthe column by way of the conduit 40. Since the condensation takes placeat a slow rate large slugs of heat are not abruptly introduced into thecolumn and the relatively large volume of retluxing liquid and oxygenproduct substantially completely maintain a constant temperature levelso that the column operation is not materially effected. Also, sincethis heat was removed from the incoming air stream, the air streamenters the high pressure zone at a corresponding lower temperature withthe result that the same heat is applied to the column during a givenperiod of operation including a number of pumping operations as in thecase of conventional operation.

The feature of mounting the transfer vessel in the enlarged vessel 37 sothat only the small volume of liquid oxygen in the chamber 39 is indirect heat interchange with the transfer vessel aids in reducingdisturbing effects` upon column operation inasmuch as only a smallportion of the liquid oxygen is directly subjected to the heat evolvedfrom the high pressure oxygen vapor.

t was mentioned above that the maximum operating frequency of theperiodic operator 50 is determined in part by the characteristics of thetransfer vessel 35. In cases where the desired pumping capacity cannotbe obtained, a pair of transfer vessels may be employed and arranged sothat one vessel is transferring liquid oxygen at high pressure whilethe'other is receiving low pressure liquid oxygen for subsequenttransfer. Ordinarily, a single transfer vessel may be properly designedto provide the necessary pumping capacity to supply the desired quantityof gaseous oxygen at the required pressure and pun'ty.

The form of the -invention illustrated in Fig. 2 of the drawings issimilar to the apparatus described above except that a differentarrangement is provided for cooling the equalizing high pressure oxygenvapor and for controlling the heat evolved during the condensingprocess. As shown, the transfer vessel 35 is provided with a cylindricalheat exchanger 60 through which a cold fluid from the fractionatingoperation passes in heat interchange relation with the transfer vessel,such as gaseous nitrogen on its way to the primary Vheat interchanger. Aconduit 61 conducts the gaseous nitrogen from the fractionating columnto the heat exchanger 60, while a conduit 62 forms the connectionbetween the transfer vessel heat exchanger and the shell 14 of theprimary heat interchanger. ln this arrangement liquid oxygen in the pool24 is fed directly to the input valve 41 by way of a conduit 63.

In operation, liquid oxygeny from the pool 24 flows into the chamber ofthe transfer vessel 35 and is conducted therefrom under the influence ofgravity at the relatively high pressure into the vaporizer section ofthe heat interchanger at a frequency controlled by the periodic valveoperator Si?. When the valve 49 closes to terminate the pressureequalizing interval, the cold gaseous nitrogen flowing through the heatexchanger 6i) cools the high pressure oxygen vapor in the transfervessel producing a pressure drop in the chamber 36 to thus effectclosure of the output valve 42 and eventual opening of the input valvelil. Thus, the heat evolved upon condensation of the oxygen vapor isconducted away from the fractionating column by the gaseous nitrogenflowing to the heat interchanger l). As a consequence, the temperatureof the column is substantially unafected by the pumping operation. Thetemperature of the gaseous nitrogen entering the heat interchanger willintermittently rise and fall thus tending to fluctuate the air feedtemperature, while at the saine time the temperature of the air enteringthe heat interchanger will fall and rise due to removal of the oxygenvapor to effect the pressure equalization. These opposite fluctuationsin the air feed temperature tend to compensate each other With aresulting substantially constant air feed temperature.

The form of the invention illustrated in Fig. 3 of the drawings includesdifferent arrangements for establishing the equalized pressureconditions for gravity flow of liquid oxygen from the column to thetransfer vessel under low pressure and for gravity flow of liquid oxygenfrom the transfer vessel the vaporizer under relatively high pressure.These arrangements are disclosed in connection with a fractionatingcycle having a primary heat interchanger l@ and a fractionating columnlll of the type disclosed in Figs. l and 2, together with the transfervessel 3S connected in the liquid oxygen path between the column andVthe heat interchanger. As shown, the transfer' vessel is fed from theliquid oxygen collecting space 243 of the column through the conduit 63controlled by the inlet valve 4l, and is connected to the lower end 45'of the vaporizer section for gravity flow through the conduit in thisform of the invention a mechanically operated valve 761 contro-ls theconduit dfi.- in place of a pressure actuated valve as employed in thepreviously described embodiments. Also, the conduit 44 functions to forman equalizing connection between the transfer vessel and the vaporizersection as well as providing a path for conducting the liquid oxygen tothe vaporizer section. The arrangement for equalizing the pressures inthe transfer vessel and the `column includes a conduit 'il connectedbetween the upper end of the transfer vessel and the vapor space in thelow pressure Zone 16 above the pool 24 of liquid oxygen. Flow throughthe conduit 7l is controlled Vby a mechanically actuated valve 72 and apressure reducing valve 73. The valves 79 and 72 are ganged together asindicated by the broken lines 74 and are controlled by a periodic valveoperator 0f the type described before. In particular, the valve operatorfunctions to simultaneously move the valves 70 and 72 to their open orclosed positions at a xed predetermined frequency. When the valve 7i) ismoved to its open position, at which time the valve 72 is simultaneouslymoved to its closed position, it will remain open for a period of timesucient for the liquid oxygen in the chamber 36 to drain therefrom underthe influence of gravity. Vv'hen the valve 79 closes, the valve 72 willopen allowing the high pressure oxygen vapor in the chamber 36 to bleedthrough the pressure reducing valve. Thus the valves 7i) and 72 arealternately opened and closed, however the valve 72 is open for agreater portion of the period of the valve operator. The high pressuregaseous oxygen conduit 46 is shown connected to two banks 75 and 76 ofhigh pressure cylinders 77 through Valves 7S and 7i. lt may be ageous insome instances to design the apparatus so that the volume of liquidoxygen fed to the vaporizer section during each transfer operation issufficient to produce the necessary quantity of gaseous oxygen to fill abank of cylinders at the desired pressure. lt is understood that thearrangements shown in Figs. l and 2 may be designed for this characterof operation if desired.

ln operation, liquid oxygen from the column flows past the valve 4l andfills the chamber 36 of the transfer vessel when the pressure in thetransfer vessel is equal to or less than the pressure of the liquidoxygen in the pool ihcreafter, when the periodic valve operator 5t)functions tcopen the valve 7th, the high pressure existing in thevaporizer section is transmitted to the chamber 36 by way of the conduitde. Since there will be some degree of vaporization in the chamber 36the liquid oxygen will flow under the influence of gravity from thetransfer vessel to the vaporizer section. At a time after the liquidoxygen has drained from the transfer vessel the periodic valve operatornoves the valve 7i) to its closed position and opens the valve 72. Highpressure vapor inthe chamber 36 then bleeds into the vapor section ofthe low pressure Zone 16 through the conduit 7l and the pressurereducing valve 73. The pressure reducing valve 74.- lowers the pressureof the oxygen vapor to correspond to the pressure in the column abovethe liquid oxygen pool 24. During this process the temperature of theoxygen vapor is materially reduced and consequently a correspondingquantity of heat is precluded from being introduced into the column.Since the pressure reducing valve 73 bleeds the transfer vessel at a lowpressure the valve 72 may be omitted if desired. In such case theperiodic valve operator 50 would control only the valve 7l?. This formof the invention eliminates the requirement of an equalizing conduit andcontrol valve connected between the high pressure end of the vaporizingsection and the transfer vessel and provides a simplified arrangementfor reducing the transfer vessel pressure to correspond to the columnpressure. Systems embodying these features comprise a compactarrangement capable of operating at high pumping efficiency with minimumdisturbing effects upon column operation.

The form of the invention illustrated in Fig. 4 of the drawings includesanother arrangement for establishing the pressure conditions in thetransfer vessel necessary to effect the pumping action. l'n thisarrangement the high pressure condition is achieved by adding sufficientheat inthe liquid oxygen in the transfer vessel to raise its temperatureto the value at which its vapor pressure exceeds the high pressure inthe vaporizer section. In particular, the transfer vessel may besimil-ar to the Fig. 2 arrangement being provided with inlet valve 4land outlet valve e2 and connected between the liquid oxygen collectingpool 24 of the column and the vaporizer section of the heat interchangerby means of conduits 63 and 44. The transfer vessel is also providedwith the heat exchanger titi for conducting uids in heat exchangerelation therewith. A substream of gaseous nitrogen from the lowpressure Zone of the fractionating column is passed directly to the heatinterchanger 10 by way of a conduit 80 while the other substream ispassed in lheat, exchange relation with the transfer vessel 35 beforeentering the primary heat interchanger. For the latter purpose, aconduit 81, two position valvular means 82, and conduits 83 and 84 areprovided for connecting the heat exchanger 60 in parallel relation witha portion of the conduit 80. The two position valvular means 82 isprovided for conducting warmed gaseous nitrogen product in heatex-change relation with transfer vessel when it is desired to increasethe temperature of the chamber 36, or cold gaseous nitrogen product whena pressure reduction is required. With the valvular means 82 in theposition shown, cold gaseous nitrogen product is passed in heat exchangerelation with the transfer vessel to reduce the temperature and hencethe pressure of the material in the chamber 36. When the valvular meansis moved to its other position, as shown in broken lines, the coldgaseous nitrogen product is conducted from the valvular means to aconduit 85, a secondary heat exchanger 86 and a conduit 87 before it ispassed in heat exchange relation with the transfer vessel 35 by way ofthe conduit 83. The secondary heat exchanger 86 is positioned about theshell 14 at the high temperature end of the primary heat interchanger,and the conduits 85 and 87 are connected thereto in such a manner as toprovide efficient heat transfer. The valvular means 82 may be providedwith a valve operator of the type disclosed in Figs. 1 and 2 or with avalve operator 88 which may comprise a spring loaded solenoidarrangement operating in response to the temperature in the transfervessel. For the latter purpose, a suitable temperature responsivecontrol device 89, such as a thermocouple, is positioned in the transfervessel and coupled to the valve operator. The pumping rate or frequencymay be determined by controlling the rate of nitrogen product flow inheat exchange with the transfer vessel by means of a valve 90 positionedin the conduit 81, or by controlling the rate of liquid oxygen flow tothe transfer vessel with a valve 91 inserted in the conduit 63. Thehighpressure gaseous oxygen conduit 46 is shown connected to two banks92 and 93 of high pressure gas cylinders through valves 94 and 95. Asdiscussed above, it may be advantageous in some instances to design theapparatus so that the volume of liquid oxygen fed to the vaporizersection during each transfer operation is suicient to produce thenecessary quantity of gaseous oxygen to fill a bank of lcylinders at thedesired pressure. Of course it is understood that the apparatus may beemployed to feed other receivers in addition to banks of high pressurecylinders.

After starting up, a substantial pressure will 'build up in thevaporizer section and, with the valvular means 82 in the position shown,cold gaseous nitrogen product will pass through the heat exchanger 60 tocondition the transfer vessel to receive liquid oxygen from .the column.When the transfer vessel -becomes filled with liquid oxygen, a lowesttemperature condition exists -in the chamber 36. In response to thistemperature condition, the temperature responsive device 89 functions tocontrol 'the valve operator 88 which moves the valvular means 82 intothe position shown in broken lines. lIn this posit-ion, warmed gaseousnitrogen product passes ,in heat exchange relation with the transfervessel. This heat exchange adds heat to the liquid oxygen `in `thechamber 36 to eventually raise its temperature to 4that valueV requiredto establish a vaporl pressure corresponding to the pressure in thevaponizer section of the heat interchan-ger 10. When the high vaporpressure is established, the valve 42 opens and liquid oxygen flowsunder the influence of gravity from the chamber 36 into the lower end ofthe vaporizer section. After the liquid oxygen has drained from thetransfer vessel, oxygen vapor will remain in .the chamber 36 atrelatively high temperature. The valve operator'88 responds to this hightemperature to move the valvular means 82 to the position shown for thepassage of cold gaseous nitrogen product in heat interchange with thetransfer vessel. The high tempeiature at which the condensing processmay be most efficiently initiated is best determined by experiment sincethe primary consi-deration is the time required for the liquid oxygen toow from the transfer vessel. In some instances therefore, t-he.crit-ical high temperature may correspond to the temperature necessary-to esta'blish lthe critical vapor pressure in the chamber 36 or to someslightly higher temperature. With the system operating at its naturalfrequency, the quantity yof liquid delivered to 4the vaporizer sectionmay exceed the demand and flood the vaporizer or the purity of theproduct may be affected. In order to control the pumping rate orfrequency, the valves or 91 may Ibe adjusted. T-he valve 90 controlslthe ow of nitrogen in heat exchange with the ,transfer vessel tocontrol the time required to establish the high and lower criticalpressures in the chamber 36, whilethe valve 91 controls the flow ofliquid oxygen to the transfer vessel and thus determine-s the time ofoccurrence of the low critical temperature.

When an empty bank of cylinders is coupled to 4the conduit 46 and liquidoxygen is transferred to the vaporizer section, the temperature of theboiling oxygen in ythe inter-changer ywill fall, and its temperaturewill subsequently increase as the vapor-ization process takes place andthe oxygen gas pressure rises. This temperature fluctuation is somewhatcompensated for in the Fig. 3 arrangement. The gaseous nitrogen entering.the heat interchanger 10 is intermittently warmed in heat exchanger 6)due to the process of condensing high pressure oxygen vapor trapped inthe transfer vessel. These periods of Agaseous, nitrogen wanming fallwithin the iow pressure lntervals of the vaporizer section and thus tendto compensate for the variations in the temperature of the boilingoxygen in the interchanger.

A form of valve that may be employed for the valves 49 of Figs. l and 2or for the valves 70 and 72 of Fig. 3 is shown in Fig. 5 lof thedrawings. This valve includes a hollow cylindrical body portion 16dprovided with an inlet opening ll and .an outlet opening 192 both ofwhich may be provided with suitable adapters, not shown, for seriallyinserting the valve in a conduit to be controlled thereby. The bodyportion 104i is provided with a cylindrical bore including an inwardlyextending flange 103 forming a concentric opening 104 of reduceddiameter. A circumferential vsalve seat 105 of knife/edge cross-sectionis formed on the upper side of the ange 103, as viewed in the drawing,adjacent the opening ldd. A cylindrical valve member 196 is slideablymounted in the body portion lili) above the flange 163 and includes alower face 107 which is adapted to contact the valve seat 105 and closecommunication through the opening 104. The valve member 106 has adiameter substantially less than the diameter of the cylindrical bore4and is provided with a plurality of radially positioned vanes 108 forslideably mounting the valve member 1Go in the valvev body portion inconcentric relation with the bore while allowing fluid flow around thevalve member. The vanos 108 have one edge secured to the valve body 19:6with the other edge slideably contacting the internal surfaces of thecylindrical bore. The diameter of the face id? is substantially greaterthan the diameter of the valve seat N5 to reduce the pressuredifferential across from vaive member 06. The valve is actuated by meansof a solenoid coil 11h positioned externally of the valve body 09. Forthis purpose the valve body portion 2.90 is fabricated from suitablenon-magnetic material, such as brass, while the valve member 196 isconstructed from steel or other highly magnetic material. The solenoidcoil il@ is properly positioned with respect to the valve member 186 tomove the valve member upwardly upon energization of the coil allowingthe fluid to flow past the valve member 106 between the vanes 108 overthe valve seat 105 and into the outlet 102 through the opening 194. Thepressure differential across the .valve member 106 is sufficientlyreduced to a va-lve for solenoid operation. The

valve may be positioned as shown with movement 'of the valve member 106along a vertical axis so that` the valve member will move in closedposition under the influence of gravity or the presence of a relativelyhigher pressure at the inlet lill may be relied upon to close the valve.Of course it is understood that the valve member may be spring biased toa closed position or arranged to be moved to closed position uponenergization lof a suitably posi* tioned coil.

There is thus provided by the present invention novel methods ofapparatus for transferring liquid p volatile liquids from a supplysource where it is held under a low pressure to a receiving means undera relatively high pressure. One of the primary features of the inventioncomprises the provision of a volatile liquid pumping process andapparatus capable of incr-ea the pressure of highly volatile liquidsfrom atmospheric pressure up to 2500 pounds per square inch gauge forexample without experiencing the common difficulty of flashing and vaporlock and without employing mechanical devices such as plunger type pumpsrequiring packing material to maintain a substantially liquid tightsystem. The principles of the present invention have special utility inconnection with processes for the fractionating of gaseous mixtures,such as air into oxygen and nitrogen, however the invention is clearlynct Ilimited to this example, wherein the energy for the pumping processis derived from the normal operation of the fractionating equipment orfrom products of the process, and wherein the over-all eiciency of thecycle is substantially unchanged as compared to the eflicieney offractionating equipment employing conventional pumping devices fordelivering high pressure gaseous oxygen for example.

Although the invention has been shown and described in several differentfor-ms, it is to be expressly understood that various changes andsubstitutions may be made therein without departing from the spirit ofthe invention. For example, the principles of the present invention arenot restricted to use in connection with fractionating systems but maybe used to pump any form of liquid, especially volatile liquids. Also,the invention may be emplof/ed equally well with single or double stagefractionating columns and with appar tus for fractionating gaseousmixtures other than air, such as in the processing of natural gas andpetroleum oils` Reference therefore will be had to the appended claimsfor a definition of the limits of the invention.

What is claimed is:

l. The method of transferring in liquid phase liquefied gas at itsboiling point from a supply reservoir where it is held at a low pressureto a receiving chamber under a relatively high pressure, which comprisesconducting under the influence of gravity liquefied gas from the supplyreservoir to a transfer zone at a level lower than the supply reservoir,establishing a pressure in the transfer zone corresponding to therelatively high pressure, conducting liouefied gas under the influenceof gravity iti the transfer zone to the receiving chamber1 and passing arelatively cold Huid in heat exchange relation with the transfer zone toreduce the pressure in the transfer Zone to the low p after theliquefied gas been conducted from the transfer zone and then placing thetransfer in communication with the supply reservoir, the relatively coldfluid being at least as cold las the low pressure liquefied gas.

2. The method of transferring in liquid phase liquefied gas at its boingpont from a supply reservoir where it is held at a low pirc to areceiving chamber under a relatively high pres t e, which comprisesconducting under the influence gravity liquefied gas from the supplyreservoir to a transfer Zone at level lower than the supply reservoir,establishing a pressure in the transfer Zone corresponding to therelatively high pressure, conducting liquefied gas under the influenceof gravity at the relatively highl pressure in the transfer Zone to thereceiv ing chamber, passing a relatively cold fluid in heat exchangerelation with the transfer zone to cool high pressure vapor remaining inthe transfer zone after liquefied gas has been conducted from thetransfer Zone to reduce the pressure in the zone and then placing thetransfer Zone in communication with the supply reservoir to receiveliquefied gas from the supply reservoir at the low pressure,therelatively cold liuid being at least as cold as the low pressureliquefied gas.

3. The method of transferring in liquid phase liquefied gas at itsboiling point from a supply reservoir where it is held at low pressureto a receiving chamber under a relatively high pressure through anintermediate transfer vessel located below the supply reservoir, whichVmethod comprises conducting under the influence of gravity liquefied gasfrom the supply reservoir to the transfer vessel at the low pressure,establishing a pressure in the transfer vessel corresponding to therelatively high pressure in the receiving chamber, conducting under theinfluence of gravity liquefied gas at the relatively high pressure inthe transfer vessel to the receiving chamber, and passing a relativelycold fluid in heat exchange relation with the intermediate transfervessel to cool relatively high pressure vapor remaining in the transfervessel after the liquefied gas is conducted to the receiv ing chamber toequalize the pressure between the supply reservoir and the transfervessel, the relatively cold liuid being at least yas cold as the lowpressure liquefied gas.

4. The method of transferring in liquid phase liquefied gas at itsboiling point from a supply reservoir where it is held at a low pressureto a receiving chamber under a relatively high pressure through atransfer vessel located below the supply reservoir, which methodcomprises the steps of transferring under the influence of gravityliquefied gas at the low pressure from the Supply reservoir to thetransfer vessel, subjecting liquefied gas transferred to the transfervessel to a vapor pressure corresponding to the relatively high pressureof the receiving chamber and simultaneously isolating the transfervessel from the supply reservoir, transferring under the influence ofgravity isolated liquefied gas at the relatively high pressure from thetransfer vessel to the receiving chamber, passing a relatively coldfluid in heat exchange relation with the transfer vessel to iiquefyhighpressure vapor remaining in the transfer vessel after the liquefiedgas is transferred to the receiving chamber to reduce the pressure inthe transfer vessel, andl placing the transfer vessel in communicationwith the supply reservoir to receive liquefied gas from the supplyreservoir at the relatively low pressure, the relatively cold fluidbeing at least as cold as the low pressure liquefied gas.

5. The method of transferring iii liquid phase liquefied gas at itsboiling point from a supply reservoir where it is held at a low pressureto a receiving chamber under a relatively high pressure, which comprisesconducting under the iniiuence of gravity liquefied gas at the lowpressure to an isolated-zone located below the supply reservoir, passinghigh pressure vapor from the receiving chamber to the isolated zone toincrease the pressure of the liquefied gas in the isolated zone tocorrespond to the relatively high pressure, conducting under theinfluence of gravity liquefied gas at the relatively high pressure inthe isolated zone to the receiving chamber, passing .a relatively cold'liuid in heat exchange relation with the isolated zone to cool highpressure vapor remaining in the isolated zone after the liquefied gas isconducted to the receiving chamber, and placing the isclated zoneY incommunication with the supply reservoir to receive liquefied gas fromthe supply reservoir, the relatively cold fluid being at least as coldas the low pressure liquefied gas. Y

6, The method of transferring in liquid phase liquefied gas at itsboiling point from a supply reservoir where it is held at a low pressureto a storage chamber under w Y 13 l a relatively high pressure throughan intermediate transfer vessel located below the supply reservoir,which method comprises conducting under the influence of gravityliquefied gas from the supply reservoir to the transfer vessel at thelow pressure, passing Vapor from the storage chamber to the transfervessel to increase the pressure in the transfer vessel to correspond tothe relatively high pressure in the storage vessel, conducting under theinfluence of gravity liquefied gas at the relatively high pressure inthe transfer vessel to the storage chamber, and passing a' relativelycold fiuid in heat exchange relation with the intermediate transfervessel to condense relatively high pressure vapor remaining in thetransfer vessel after the liquefied gas is conducted to thestoragechamber to equalize the pressure between the transfer vessel and thesupply reservoir, the relatively cold fluid being at least as cold asthe low pressure liquefied gas.

7. The method of transferring in liquid phase liquefied gas at itsboiling point from a supply reservoir where it is held at a low pressureto a storage chamber under a relatively high pressure through anintermediate transfer vessel located below the supply reservoir, whichmethod comprises conducting under the influence of gravity liquefied gasfrom the supply reservoir to the transfer vessel at the low pressure,establishing a vapor pressure in the transfer vessel at least equal tothe relatively high pressure in the storage chamber to increase thepressure of the liquefied gas in the transfer vessel to correspond tothe relatively high pressure in the storage chamber, conducting underthe influence of gravity liquefied gas at the relatively high pressurein the transfer vessel to the storage chamber, and passing a cold fiuidin heat exchange relation with the transfer'vessel to condense highpressure vapor remaining in the ltransfer vessel after the liquefied gasis conducted to the storage chamber to equalize the pressure between thesupply reservoir and the transfer Vessel, the relatively cold fiuidbeing at least as cold as the low pressure liquefied gas.

S. The method of transferring in liquid phase liquefied gas at itsboiling point from a supply reservoir where it is held at a low pressureto a storage chamber under a relatively high pressure through anintermediate transfer vessel located below the supply reservoir, whichmethod comprises conducting under the influence of gravity a stream ofliquefied gas from the supply reservoir to the intermediate transfervessel at the low pressure, periodically establishing a vapor pressurein the transfer vessel at least equal to the relatively high pressure inthe storage chamber, conducting under the influence of gravity liquefiedgas at the relatively high pressure in the transfer vessel to thestorage chamber, and passing a relatively cold uid in heat exchangerelation with the intermediate transfer Vessel to condense high pressurevapor remaining in the transfer Vessel after the liquefied gas istransferred to the storage chamber to reduce the pressure in thetransfer vessel lto at least equal the low pressure in the supplyreservoir, the relatively cold tiuid being at least as cold as the lowpressure liquefied gas, the period for establishing a vapor pressure inthe transfer vessel at least equal to the relatively high pressure beinglonger than the total time required for the transfer of liquefied gasfrom the transfer vessel, the condensation of high pressure 'vaporremaining in the transfer vessel and the transfer of liquefled gas fromthe supply reservoir to the transfer vessel.

9. The method of transferring in liquid phase liquefied gas at itsboiling point from a supply reservoir Where it is held at a low pressureto a storage chamber under a relatively high pressure through anintermediate transfer vessel located below the supply reservoir, whichmethod comprises conducting under the influence of gravity liquefied gasfrom the supply reservoir to the'transfer vessel at the low pressure,passing a warm fluid in heat exchange relation with the transfer vesselto establish a vapor pressure in the transfer vessel corresponding tothe relatively high pressure in the storage chamber, conducting underthe iniiuence of gravity Vliquefied gas at the relatively high pressurein the transfer vessel to the storage cham-ber, andpassing a cold fluidin heat exchange relation with the transfer vessel to cool high pressurevapor remaining in the transs'fer vessel after the liquefied gas isconducted to the storage chamber and equalize the pressure in thetransfer vessel and the supply reservoir, therelatively cold fluid beingat least as cold as the low pressure liquefied gas.

10. The method of transferring in liquid phase liquefied gas at itsboiling point from a storage reservoir where it is held at a lowpressure to the reservoir of a vaporizer under a relatively highpressure through an intermediate transfer vessel located below thesupply reservoir, the vaporizer being operable to deliver liquefied 4gasin gas'- eous phase under the relatively high pressure, which methodcomprises conducting under the influence of gravity liquefied gas fromthe supply reservoir to the transfer vessel, transferring heat from thevaporizer to the transfer vessel to increase the pressure of theliquefied gas in the transfer vessel to correspond to the relativelyhigh pressure in the vaporizer, isolating thetransfer vessel from thestorage reservoir in response to the relatively high pressure in thetransfer vessel and conducting under the influence of gravity liquefiedgas at the relatively high pressure to the reservoir, vaporizing liquidmaterial in the reservoir, isolating the transfer vessel from thereservoir at the beginning of the vaporizing step, passing a relativelycold fiuid in heat exchange relation with the transfer vessel to reducethe pressure in the transfer vessel to the low pressure, and conductingliquefied gas from the supply reservoir to the transfer vessel duringthe vaporizing step, the relatively cold fluid being at least as cold asthe low pressure liquefied gas,

ll. The method of transferring in liquid phase liquefied gas at itsboiling point from a supply vessel where it is held at a low pressure toa receiving chamber under a relatively high pressure, which comprisesconducting under the iniiuence of gravity liquefied gas from the supplyreservoir to a transfer Zone located below the supply vessel,establishing a pressure in the transfer zone corresponding to therelatively high pressure responsively to the temperature in the transferzone, conducting liquefied gas under the influence of gravity at therelatively high pressure in the transfer zone to the receiving chamber,and passing a relatively cold fluid in heat exchange relation with thetransfer zone to reduce the pressure of high pressure vapor remaining inthe transfer Zone after the liquefied gas has been conducted from thetransfer zone and placing the transfer zone in communication with thesupply reservoir resp-onsively to the temperature in the transfer zone,the relatively cold fiuid being at least as cold as the low pressureliquefied gas.

l2. The method of transferring in liquid phase liquid product of afractio'nating operation to a receiving cham ber at a relatively highpressure, in which operation compressed and cooled gaseous mixture isfractionated into a gaseous fraction and a liquid fraction as theproduct,l which method comprises conducting under the in fiuence ofgravity liquid product from the fractionating operation to an isolatedzone, establishing a pressure in the Zone corresponding to therelatively high pressure, conducting under the iniiuence of gravityliquid` product atthe relatively high ypressure in the Zone to thereceiv ing chamber, and passing cold fluid from the fractionatingoperation in heat exchange with high pressure vapor re? maining in thezone after liquid product is conducted to the receiving chamber, andplacing the Zone in communication with the fractionating operation toreceive liquid product from the fractionating,operation.

13. The method of transferring in liquid phase liquid product of afractionating operation to a receiving chamber at a relatively highpressure through an intermediate transfer vessel, in which operationcompressed and cooled gaseous mixture is fractionated into a gaseousfraction and a liquid fraction vas the product, which method comprisesconducting under the inuence of gravity liquid product from thefractionating operation to the transfer vessel, transferring heat fromthe receiving chamber to the transfer vessel to increase the pressure ofliquid product in the transfer vessel to correspond to the relativelyhigh pressure in the receiving chamber, conducting under the influenceof gravity liquid product at the relatively high pressure in thetransfer vessel to the receiving chamber, and passing cold fluid fromthe fractionating operation in heat exchange relation with the transfervessel to cool high pressure vapor remaining in the transfer vesselafter liquid product is conducted to the receiving chamber and place thetransfer vessel in communication with liquid product in fractionatingoperation.

14. The method of transferring in liquid phase liquid product of afractionating operation to a vaporizing process under a relatively highpressure through an intermediate transfer vessel, in which operationcompressed and cooled gaseous mixture is fractionated into gaseousfraction and liquid fraction as the product and in which process liquidproduct is converted into gaseous phase at the relatively high pressureby heat exchange with gaseous mixture on its way to the fractionatingoperation, the method comprising withdrawing liquid product from thefractionating operation and conducting under the influence of gravityliquid product to the transfer vessel at the pressure of liquid productin the fractionating operation, establishing a vapor pressure in thetransfer vessel corresponding to the relatively high pressure in thevaporizer, conducting under the inuence of gravity liquid product at therelatively high pressure in the transfer vessel to the vaporizer, andpassing cold fluid from the fractionating operation in heat exchangerelation with the transfer vessel to cool vapor remaining in thetransfer vessel after liquid product is conducted to the vaporizer andestablish a pressure equalization between li uid product in thefractionating operation and the transfer vessel,

15. The method of transferring in liquid phase liquid product of afractionating operation to a vaporizing process under a relatively highpressure through transfer vessel, in which operation a compressed andcooled gaseous mixture is fractionated into gaseous fraction and liquidfraction as the product and in which process liquid product is convertedinto gaseous phase at the relatively high pressure by heat exchange withgaseous mixture on its way to the fractionating operation, the methodcomprising withdrawing liquid product from the fractionating operationand conducting under the influence of gravity liquid product to thetransfer vessel at the pressure of the liquid product in thefractionating operation, periodically establishing a vapor pressure inthe transfer vessel corresponding to the relatively high pressure,conducting under the iniiuence of gravity liquid product at therelatively high pressure Vin the transfer vessel to the vaporizingprocess, passing cold fluid from the fractionating operation in heatexchange relation with the transfer vessel to liquefy high pressurevapor remaining in the transfer vessel after liquid product is conductedto the vaporizing process and equalize the pressure between liquidproduct in the fractionating operation and the transfer vessel, theperiod of the periodic establishment of vapor pressure in the transfervessel being longer than the total time required to conduct highpressure liquid product to the vaporizing process, to liquefy highpressure vapor remaining in the transfer vessel and to conduct liquidproduct from the fractionat ing operation to the transfer vessel.

16. The method of transferring in liquid phase liquid product of afractionating operation to a vaporizing process under a relatively highpressure through a transfer vessel, in which operation compressed andcooled gaseous mixture is fractionated into gaseous fraction and liquidfraction as the product and in which process liquid product is convertedinto gaseous phase at the relatively high pressure by heat exchange withgaseous mixture on its way to the fractionating operation, the methodcomprising withdrawing a portion of liquid product from thefractionating operation and conducting under the innuence of gravitywithdrawn lliquid product to the transfer vessel at the pressure ofliquid product in the fractionating operation, conducting high pressurevapor from thc vaporizing process to the transfer vessel to increasethetpressuretof liquid product in the transfer vessel to correspond tothe relatively high pressure in the vaporizing process, conducting underthe intiuence of gravity liquid product at the relatively high pressurein the ransfer vessel to the -vaporizing process under the iniiuence ofgravity, and passing cold uid from the fractionating operation in heatexchange relation with the transfer vessel to liquefy high pressurevapor remaining in the transfer vessel after conducting liquid productto the vaporizing process and equalize the pressure between the transfervessel and liquid product in the fractionating operation.

17. The method of transferring in liquid phase liquid product Vof afractionating operation to a vaporizing process under a relatively highpressure through a transfer vessel, in which operation compressed andcooled gaseous mixture is fractionated into gaseous fraction and liquidfraction as the product and in which process liquid product is convertedinto gaseous phase at the relatively high pressure by heat interchangewith gaseous mixture on its way to the fractionating operation, themethod comprising withdrawing liquid product from the fractionatingoperation and conducting under the influence of gravity liquid productto the transfer vessel at the pressure of the liquid product in thefractionating operation, passing warmed fluid from the vaporizingprocess in heat exchange relation with the transfer vessel to establisha vapor pressure in the transfer vessel corresponding to the relativelyhigh pressure in the vaporizing process, conducting under the iniiuenceof gravity liquid product at the relatively high pressure in thetransfer vessel to the vaporizing process, passing cold fluid from thefractionating operation in heat exchange relation with the transfervessel to cool high pressure vapor remaining in the transfer vesselafter liquid product is conducted to the vaporizing process and equalizethe pressure between the transfer vessel and liquid product in thefractionating operation, and controlling the now of warmed fluid and theiiow of cold uid in heat'exchange relation with the transfer vessel inaccordance with the temperature of the transfer vessel.

18. The method of transferring in liquidV phase liquid product of afractionating operation to a vaporizing process under a relatively highpressure through a transfer vessel, in which operation compressed andcooled gaseous mixture is fractionated into gaseous fraction and liquidfraction as the product and in which process liquid product is convertedinto gaseous phase at the relatively high pressure by heat exchange withgaseous mixture on its way to the fractionating operation, the methodcomprising withdrawing a portion of liquid product from thefractionating operation and conducting under the influence of gravitywithdrawn liquid product to the transfer vessel at the pressure of theliquid product in the fractionating operation, passing warmed uid fromthe vaporizing process in heat'exchange relation with the transfervessel in response to a low temperature in the transfer vesselapproaching the temperature of the liquid product,vthe heat exchangebetween the warmed uid and the transfer vessel establishing a vaporpressure in the transfer vessel corresponding to the relatively highpressure in the vaporizing process, conducting under Vthe influence ofgravity liquid product in the transfer vessel at the relatively highpressure to the vaporizing process,

passing cold fluid from the fractionating operation in heat exchangerelation with the transfer vessel in response to a high temperature inthe transfer vessel approaching the temperature of the vapor at theratively high pressure, the heat exchange between the cold fluid and thetransfer vessel liquefying high pressure vapor remaining in the transfervessel after liquid product is conducted to the vaporizing process andestablishing pressure equalization between the transfer vessel andliquid product in the fractionating operation.

19. Apparatus for transferring in liquid phase a volatile liquid productfrom a fractiona-ting operation t-o a heat interchanger under arelatively high pressure in which heat exchange liquid product forfeitscold to a compressed gaseous mixture on its way to the fractonatingoperation and emerges in gaseous phase under the relatively highpressure, and in which operation the cooled gaseous mixture isfractionated to produce volatile liquid at a low pressure as theproduct, comprising a transfer vessel, means for conducting under theinfluence of gravity liquid product from the fractionating operation tothe transfer vessel at the low pressure and for conducting under theinuence of gravity liquid in the transfer Vessel to the heatinterchanger at the relatively high pressure, the lastnamed meansincluding means for periodically establishing a pressure in the transfervessel at least equal to the relatively high pressure in the heatinterchanger and means for passing cold fluid from the fracti-onatingoperation in heat interchange relation with the transfer vessel to coolhigh pressure vapor remaining in the transfer vessel after liquid isconducted to the heat interchanger and reduce the pressure in thetransfer vessel to a value at least equal t-o the pressure of liquidproduct in the fractionating operation.

20. Apparatus for transferring in liquid phase a volatile liquid productfrom a fractionating operation to a heat interchanger, under arelatively high pressure in which heat interchanger liquid productforfeits cold to gaseous mixture on its way to the fractionatingoperation and emerges in gaseous phase under the relatively highpressure, and in which operation the gaseous mixture is fractionated toproduce volatile liquid as a product, comprising a transfer vessel, andmeans for conducting under the inuence of gravity liquid product fromthe fractionating operation to the transfer vessel at the pressure ofthe liquid product in the fractionating oper-ation and conducting underthe influence of gravity liquid in the transfer vessel lto the heatinterchanger at the relatively high pressure, the last-named meansincluding an equalizing conduit connected between the heat interchangerand the transfer vessel, periodically operable valvular means forintermittently opening and closing the equalizing conduit, and means forpassing cold fluid from the fractioning operation in heat exchangerelation with te transfer vessel.

21. An apparatus of the character set forth in claim 20 in which thetransfer vessel is positioned in an auxiliary vessel lled with volatileliquid product from the fraction-ating operation and in which thetransfer vessel is constructed of a material having a low thermalconductivity.

22. Apparatus for transferring in liquid phase a liquid product from theliquid product collecting space of a fractionating operation to a heatinterchanger under a relatively high pressure, in which heatinterchanger liquid product forfets cold to gaseous mixture on its w-ayto the fractionating operati-on and emerges in gaseous phase under therelatively high pressure, and in which operation the gaseous mixture isfractionated to produce volatile liquid as a product, comprising atransfer vessel, conduit means connecting the transfer vessel betweenthe liquid produc-t collecting space and `the heat interehanger forliquid llow under the influence of gravity from the fractionatingoperation through the transfer vessel to the heat interchanger, valvularmeans operative responsively to a pressu-re in the transfer vessel nogreater than the pressure of liquid product in the fractionatingoperation for the flow of liquid under the inuence of gravity from thefraction-ating operation to the transfer vessel and operativeresponsively to another pressure in the transfer vessel at least equallto the pressure in the heat interchanger for the ow of liquid under theinfluence of gravity from the transfer vessel to the heat interchanger,a heat exchanger surrounding the transfer vessel, conduit meansincluding valvular means for alternately passing cold iiuid from thefractionating operation and warmed fluid from the fractionatingoperation lthrough the heat exchanger, means for operating the valvula-rmeans .and means responsive to the temperature of the transfer vesselfor controlling the lastnamed means.

23. Apparatus for transferring in liquid phase a volatile liquid productfrom a fractionating operation to a heat interchanger under a relativelyhigh pressure in which heat exchange liquid product forfeits cold to acompressed gaseous mixture on its way to the fractionating operation andemerges in gaseous phase under the relatively high pressure, and inwhich operation the cooled gaseous mixture is fractionated to pro-ducevolatile liquid at a low pressure as lthe product and a cold gaseousfraction, comprising a transfer vessel, means for conducting under theinfluence of gravity liquid product from the fractionating operationyt-o the transfer vessel at the low pressure and for conducting underthe inuence of gravity liquid in the transfer vessel to Athe heatinterchanger at the relatively high pressure, the last-named meansincluding means for periodically establishing a pressure in the transfervessel at least equal to the relatively high pressure in the heatinterchanger `and means for passing cold gaseous fraction from thefractionating operation in heat interchange relation with the transfervessel to cool high pressure vapor remaining in the transfer vesselafter liquid is conducted to the heat interchanger and reduce thepressure in the transfer vessel to a value 'a-t least equal to thepressure of liquid product in the fractionating operation.

References Cited in the file of this patent UNITED STATES PATENTS924,141 Brown June 8, 1909 1,976,336 Eichelman Oct. 9, 1934 2,001,353Saluikoff May 14, 1935 2,035,396 Mesinger Mar. 24, 1936 2,052,855 TwomeySep-t. 1, 1936 2,107,797 `Messer Feb. 8, 1938 2,217,467 Bohndud Oct. 8,1940 FOREIGN PATENTS 344,039 Germany Aug. 8, 1915 469,939 Great BritainAug. 3, 1937

